I own K5 since Easter along with my K10d and K100d Super. During summer I bought a small Metz flash to help my older cameras with low light indoor shooting. I first tried Metz 24 AF-1, which I returned and replaced with Metz 36 AF-5.

I had not used it on K5 since this camera has the reported flash exposure issue. It is suggested to us it with auto thyristor capable flashes. But last week I went to a kid's birthday party and tried the K5+Metz36 combination to see how intense the problem is

Well, I am more than pleased to say that even I tried to produce the worst conditions that present the problem (zoom in and out while at the same time change the flash from direct to bounch and vise versa) only 2 shoots out of ~150 had an overexposure issue. Better or at least equal to the metering/exposure without a flash.